Gas producer of the rotary grate type



' y 7, 1940- K. KOLLER. 2,200,066

ms PRODUCER OF THE ROTARY GRATE TYPE Filed Dec. 14, 1938 I 20 4 /22 I Q 73 i g 1 5 73 73 75 i F 5 11 F lPatentecl May 7, 19441? i c-As raccoons,

Karl Keller, Budapest, l lu'ng-gzury Application December 14, 1938, Serial No.

- InGcrinany December 27, 1937 7 Claims.

' My invention relatesto gas producers-more especially of the rotary-grate type fitted, with cutter; members. It'is an object of, this invention to improve this type .of producer with a view to avoiding obstructions of the'ash-pan by deposits forming thereon, and irregularities in the dis-- charge of the slag whereby the operation of the gas producer might be hampered. Gas'producers of the rotary grate type with 1 cutter members are well known (see British Patent 7,330 of 1911). The main features, of these as producers consist in this, that below the shell of'the gas producer a rotatable, waterfilled ash-pan is provided, the slightly coned bottom of which carries in the middle a nozzle like grate and, extending from the middle towards-the periphery, a plurality of curved transporting and shearing cutters, so-callcd milling cutters, having an inclined working surface, which operate uniformly on the whole of the bottom surface of the fuel column and displace the slag towards the periphery; From the ash-pan :the, displaced slag is removed by means of a plough-like scraper member which is fixed to a submerged ring which is rigidly connected to'the lower end of the gas producer shelland extends into the ashpan. According to a further proposal by the applicant (see British Patent 236,725) stemming members, Smcalledstemming '1 shears, are provided on'the outside of the submerged ring, the lower edge of which members together with the upper edges of the milling cutters exert a shearing action on the lumps of slag in a plane parallel to the bottom of the ashman. These gas producers have been found to work very well in practice and are in. use in a great number of works, giving excellent. results. It has been found, however, that in some circumstances a cement-like deposit may form-on the bottom of the ash-pan between the milling cutters, which. in the first place reduces in an unfavorable manner the space in which the milling cutters operate and may in time when the plant is in continuous operation grow to such an extent that the operation of the milling cutters is entirely obstructed, resulting in a reduction in the capacity of the gas producers and a disturbance of the gasification process.

This undesirable phenomenon 1113 5 be ac counted for as follows: During the charging of the gas producers a sorting of the coal according to its sizeof grain. takes place, the larger pieces of coal sliding towards the shell of the gas prc I ducer, whilst the coal dust falls'down in the mid dle. This distribution of "the coal according to the size of grain remains unchanged in the fuel column during its passage through the gas producer, so that, after the formation of slag in the lower part of the gas producer, the fine ash slides down in the middle part and the larger pieces of slag on the outer part of the ash-pan bottom. With kinds of coal which contain much dust and the ash of which, owing to its chemical composition, shows a tendency to bind hydraulically, it frequently occurs thatthe fine ash;

formed from the coal dust and sliding down in paras, orr cs flit THE ROTARY GRATE TYPE 1 Y "(r ff the middle becomes bound under the influence of the water contained in the ash-pan, so that it hardens as a solid deposit betweenthe milling cutters.

A further disadvantage of these gas producers, which has often. been observed, consists in this that the discharged slag contains large lumps. The reason for this is, thatthelarger pieces of slag are exposed during the coaction of the stemming members with the milling cutters to ashearing action only in an approximately horizontal plane. They are thus cut up in an irregular manner, in accordance with the manner which they lie between the coacting edges, which may result in irregularities in the discharge of the slag and consequently in the operation of the gas producer.

The main object of the invention is to overcome these disadvantages of the rotary grate gas producers operating with milling cutters, described above. For this purpose the milling cutters, which preferably have a. vertical operating surface, are according to the invention arranged only at the periphery of the raised middle part of the ash-pan bottom, which has the form of a steep surfaceof revolution, each being provided with a vertical shield. Furthermore, the stemming shearing members are disposed in such a manner at the inside of the wall of the submerged ing that their edges coact both with the vertical edges of the shields and also with the inclined edges of the milling cutters, whereby the pieces ofslag are subjected during the rotary motion of the ash-pan to a shearing and breaking action a vertical and in an inclined plane. The rotary surface forming the middle part of the ash-pan bottom may have the formof a straight or of an inwardly curved cone-like surface or may consist of two conical surfaces, the inner one of which is steeper than the outer one.

The invention also has for its purpose to overcome the disadvantage of therotary grate gas producers operating with milling cutters, that the resistance of the material increases considerably in front of the scraper member which is fixed to the immersed ring, whilst behind this member it suddenly drops, so that at the last named place considerably more material emerges from the gas producer than at the other places, which may lead to the coal column sinkingdn an irregular manner in the gas producer and to the fire becoming inclined. In order to avoid this undesirable phenomenon as well, according to a further modification of the invention the discharging space of the ash-pan is in the region of the scraper member separated from the interior of the gas producer by a partition which extends parallel to the submerged ring.

The details and the manner in which the gas producer according to the invention operates shall now be more particularly described with reference to the accompanying drawing, showing by way of example and in a purely diagrammatic manner, an embodiment of my invention, in which Fig. 1 is a longitudinal section through the gas producer,

Fig. 2 a cross-section of the same on the line II-II of Fig. 1,

Fig. 3 is a portion of Fig. 1 with the milling cutters and shields and the stemming shearing members, drawn to a larger scale, and

Fig. 4 is a section on line IVIV of Fig. 3.

Referring to the drawing, the gas producer consists as usual of a shell 1 with a cover plate 2, a charging device 3 and an outlet branch 3, also of a submerged ring 4 which is fixed to the lower end of the shell and extends into an ash-pan 6 which is rotatable by means of the drive and supports the nozzle-like grate formed of rings 7. To the grate is connected the supply pipe 8 for the gasifying means.

According to the invention the middle part of the ash-pan bottom has the form of a steep surface of revolution, the generating lines of which, at least in the middle part of the gas producer, that is in the region of the fine ash, are inclined at an angle of about 45. In the example shown, it consists either of two conical surfaces It and H (see lefthand half of Fig. 1)', of which the iner one is steeper than the outer one, or of an inwardly curved cone-like surface l2, (see righthand half of Fig. 1). At the outer part of the surface of revolution, for instance in the firstnamed arrangement at the less steep conical surface H, the short milling cutters 13 are provided, which extend to below the immersed ring, consist of vertical plates bent for instance in accordance with a logarithmic spiral and are offset at M. Fitting closely to the offset part of the milling cutters are the upwardly extending shields l5 formed by vertical plates, which are fixed to the milling cutters, for instance by means of screws.

IS. The shields l5 are shorter than the milling cutters l3, so that there is a gap between the vertical inner edges of the shields and the inside of the wall of the immersed ring 4. Between the upper edges of the milling cutters and the lower edge of the immersed ring there is also a gap.

To the inside of the wall of the immersed ring are fixed at the bottom the stemming shearing members l8 which consist for instance of pieces 1 of the milling cutters by one, that is to say, if there is an even number of milling cutters, there.

is an uneven number of stemming bodies. To the immersed ring is also fixed the scraper member IS with adefiecting plate 20.

the immersed ring by means of ribs 22 In the region of the scraper member the discharging space of the ash-pan is separated from the interior of the 1 gas producer by the partition 2| which is'fixed to I I operates in the following manner: The fine ash formed in the middle part of the gas producer;

slips down on the steeply inclined bottom [0 or I2 of the rotating ash-pan under the action of the coal column resting on it and is carried along by the sliding down larger lumps of slag which are formed in the outer zones of the gas producer, and which are themselves displaced by the milling cutters I3 out of the space within the gas producer and are broken up by the shearing-and breakingactio-n of the coacting edges (indicated in 3 by somewhat heavier lines) of the stemming plates l3 and the shields i5 and the milling cutters I3 respectively. As will. be seen from Fig.

3 the coacting shearing edges have an L-likeform} that is to say the cutting action takes place both in a vertical and in an inclined plane, resulting in v a uniform breaking up of the slag. The displaced and uniformly broken up slag falls on tov the flat peripheral part of the ash-pan bottom, from which it is discharged by the scraper membenlS.

The discharged slag is prevented from falling back into the interior of the gas producer by the parti v j.

tion 20.

As will be seen from the above description of the mode of operation of the arrangement illuS- trated, the problems put forward at the beginning of the specification are completely solved. The

fine ash reaching the steep part o-fthe ash-pan bottom can slide down unhindered on the same, during which it cannot'beco-me boundgas it does not come in contact with Water. It canalsonot accumulate between the milling cutters, as these cutters are arranged only at the periphery of the steep part of the ash-pan bottom, that is in the region of the larger pieces of' slag, where there is no danger of an accumulation of slag. In this region the fine ash is necessarily carried along by the larger pieces of slag, so that it can no longer have any detrimental efiect. V

Furthermore, through the .coaction of the shields and the milling cutters on the one hand and the stemming bodies on the other hand auniformly broken up slag is obtained, which favorably affects both the gas producing processand also the discharge of the slag and also facilitates the further disposal of the slag. The ar angement of the partition described also has a considerable'share in rendering the gas producer process uniform.

Finally, owing to the fact that the number of milling cutters difiers from that of the stemming bodies suitably by one, only a single pair of shearing and breaking elements will at any time be operative, so that the resistance which.

occurs during the breaking up of the slag is effective only at one place at a time. Should the number of the two elements be equal, all the pairs of shearing and breaking" elements would operate at the same time, which would result in the work of breaking up the slag being considerable greater. I wish it to be understood that I do not desire will occur to a person skilled'inthe art.

ash-pan bottom has the form of an inwardly I claim:

1. A gas producer comprising in combination, a rotatable Water-filled ash-pan, milling cutters and a submerged ring extending into said ash-pan, a scraper member and a plurality of stemming shearing members on said ring, said milling cutters being arranged only at the periphery of the middle part of the ash-pan bottom, which has the form of a steep surface of revolution, a vertical shield on each milling cutter, said shear members being so arranged on the inner wall of said ring that their edges are free to coact both.

with the vertical edges of said shields and with the inclined edges of said milling cutters.

2. The gas producer of claim 1, in which said milling cutters have a vertical working surface.

3. The gas producer of claim 1, in which the middle part of the ash-pan bottom has the form of a straight cone-like surface.

4. The gas producer of claim 1, in which the curved cone-like surface.

5. The gas producer of claim 1, in which the middle part of the ash-pan bottom consists of two conical surfaces, which surfaces are continuous with respect to each other of' which the inner one is steeper than the outer one, while the milling cutters are arranged on the outer conical surface.

6. The gas producer of claim 1, in which the shields are fixed on the milling cutters and the milling cutters extend below the submerged ring in such manner that a gap is left between their outer edges and the submerged ring.

7. The gas producer of claim 1, in which the number of milling cutters differs by one from the number of stemming shearing members.

KARL KOILER. 

